Water Fluoridation

This past March, Mayor David Stahl of East Brunswick, NJ denounced tap water fluoridation as “mass medication of the public.” An ethical labyrinth, it infringes on informed consent and individual choice, but it also represents a commitment to public health, especially for people lacking the time and money to treat dental issues. Proponents hail fluoridation as one of the top public health successes of the twentieth century. Ever since Michigan started fluoridating its water supply in 1945, tooth decay — the number one chronic disease in children — has dropped by 25%. Many respected institutions, such as the American Dental Association (ADA), the World Health Organization (WHO), and the Centers for Disease Control and Prevention (CDC) openly support fluoridation.

Calcium fluoride from fluorite (left) is a naturally-occurring source of fluoride in water.

What is the science behind how fluoride protects teeth? The original theory was that fluoride hardens the tooth surface by converting the main component of enamel, hydroxyapatite, into fluorapatite — which is far less prone to dissolve in acid. But recent research has shown that the fluorapatite layer is at least 10 times thinner than previously believed, and easily worn away by normal chewing. A different theory suggests that fluoride directly disrupts the enzyme processes bacteria use to survive, preventing them from sticking on teeth and causing damage.

Why is there opposition to something shown to have such great health benefits? Stahl had ethical qualms about fluoridation, but some fear possible adverse health effects. According to the Fluoride Action Network (FAN), studies have associated fluoride with lowered IQ and increased risk of cancer, bone fractures, and arthritis. In response, the ADA cited contrary research showing no correlation between fluoridation and these risks. They point out that the fluoride levels in the IQ studies, which were conducted in countries with fewer regulations, are far higher than those allowed in the United States. FAN also asserts that there isn’t enough research on the safety of fluorosilic acid (the main fluoridating compound added to water supplies), that the studies involved in launching fluoridation were flawed, and that sensitive individuals can suffer from frustrating symptoms such as fatigue, migraine, and gastrointestinal disturbances. However, proponents point to the fact that nearly three-quarters of Americans live in areas with fluoridated water with no apparent ill effects, and that many highly-respected organizations endorse fluoridation (of course, neither of these last two reasons are actually valid arguments — opponents suffer from the same fallacy when they argue that 97% of Western Europe does not fluoridate its water).

“Fluoride hardens the tooth surface by converting the main component of enamel, hydroxyapatite, into fluorapatite — which is far less prone to dissolve in acid. But recent research has shown that the fluorapatite layer is at least 10 times thinner than previously believed, and easily worn away by normal chewing.”

Yet it seems there are some doubts about fluoridation that pro-fluoridationists have been unable to address. A 2015 study in England found a 30% higher incidence of hypothyroidism — an autoimmune condition marked by fatigue, hair loss, and depression, among other symptoms — in areas where drinking water is fluoridated. In another study, Harvard researcher Elise Bassin found that men who drank fluoridated water during a critical period of growth between ages six and eight were at least five times more likely to develop osteosarcoma. It was later suspected that her thesis advisor, Chester Douglass, who was also a consultant for the fluoridated toothpaste manufacturer Colgate, tried to cover up the results.

The debate also rages over the significance of dental fluorosis, a condition associated with fluoride intake during childhood. Proponents of fluoridation claim that mild cases, marked by bleached streaks on teeth, have merely a cosmetic effect. But in rare severe cases, people exhibit weakened, mottled teeth. Just this spring, the CDC reduced its recommended maximum fluoride level to 0.7 mg/L (down from its 1962 guideline of 0.7-1.2 mg/L), citing concerns over high rates of the fluorosis, now affecting 40% of young teenagers (double the rate of the late 1980s). Even though most cases are mild, there is reason to believe that fluorosis may not only be cosmetic but also systemic.

Without enough dietary intake of calcium or magnesium, fluoride’s high reactivity can make teeth more brittle and disrupt their natural mineralization cycles, explaining the symptoms of severe fluorosis. It also accounts for fluoride’s aforementioned interaction with sensitive bacterial enzymes, which suggests that fluoride can interfere with human enzymes and bone formation. These effects may explain the observed associations with cancer, hypothyroidism, and neurotoxicity. Research suggests that solely topical use of fluoride, such as by toothpaste or fluoride rinse, can achieve the same protective effects without fluorosis or associated risks, possibly illuminating why European countries that discontinue water fluoridation have not seen a resurgence of tooth decay.

“European countries that discontinue water fluoridation have not seen a resurgence of tooth decay.”

But just to be clear, drinking any amount of fluoride can’t prevent cavities quite like good oral hygiene — and not to mention, cutting out those sodas and sweets.